Gaeta listens to this explanation, first with an expression of polite bafflement, then growing interest as the description takes proper shape in his mind. "Yeah," he says. "Honestly, that sounds like a good puzzle for a navigator -- you're rotating a three-dimensional object in what could be trillions of permutations, then have to reverse-engineer it back to the starting point. If you don't have the right spatial reasoning skills, you'll have a much harder time solving it."

Bids start to circulate; Gaeta murmurs call and puts in a few more acorns.